This invention relates to a circuit breaker with auxiliary devices such as a warning switch and an auxiliary switch.
A conventional circuit breaker will be described with reference to FIGS. 21 through 27. FIG. 21 is a perspective view showing the external appearance of the conventional circuit breaker. FIG. 22 is an exploded perspective view of the circuit breaker. FIG. 23 is a sectional view taken along line 23--23 in FIG. 21, showing the circuit breaker which is in an "on" state. FIG. 24 is also a sectional view taken along line 23--23 in FIG. 21, showing the circuit breaker which is in an "off" state. FIG. 25 is a sectional view taken along line 23--23 in FIG. 21, showing the circuit breaker which is in a "trip" state. FIG. 26 is a sectional view taken along line 26--26 in FIG. 22, showing an auxiliary cover. FIG. 27 is a perspective bottom view of the auxiliary cover.
In those figures, reference numeral 1 designates a circuit breaker casing comprising a base 1a, and a main cover 1b which is detachably secured to the base 1a; 2, an auxiliary device such as a warning switch and an auxiliary switch; 3, a recess formed in one surface of the main cover 1b which is opposite to the other surface which is on the side of the base 1a, for receiving the auxiliary device 2; 5, a movable piece which is swingably mounted inside the circuit breaker casing 1, having a movable contact 5a; and 6, a stationary piece with a stationary contact 6a which is brought into and out of engagement with the movable contact 5a; 7, a handle which is pushed back and forth to swing the movable piece 5 with the aid of a toggle link mechanism 8. The handle 7 comprises: a arcuate base 7a which is moved along the inner surface of the main cover 1b, and an operating protrusion 7b which is extended outwardly from the arcuate base 7a through an opening of the main cover 1b. Further in those figures, reference numeral 9 designates a lever operated in association with the toggle link mechanism 8; 10, a trip cover coupled to the lever 9 through an engaging metal part 11 and a latch 12; and 13, a tripping mechanism (of bimetal type or electromagnetic type) which is connected to a terminal board 14 on the side of load and connected through a flexible stranded wire 15 to the movable piece 5.
The operation of the conventional circuit breaker thus constructed will be described.
It is assumed that the circuit breaker is held turned on. When, under this condition, the handle 7 is moved in the direction of the arrow 16, the toggle link mechanism 8 is bent, whereby the movable piece 5 is raised. As a result, the circuit breaker is turned off as shown in FIG. 24. When, under this condition, the handle 7 is moved in the direction of the arrow 17 as shown in FIG. 24, the toggle link mechanism 8 is stretched, whereby the movable piece 5 is depressed. As a result, the circuit breaker is turned on as shown in FIG. 23. When over-current flows in the circuit breaker in the "on" state as shown in FIG. 23, the tripping mechanism 13 is operated to turn the trip bar 10 in the direction of the arrow 18, so that the engaging metal part 11 and the latch 12 are disengaged, and the lever 9 is elastically raised. As a result, the toggle link mechanism is bent to raise the movable piece 5. Thus, the circuit breaker is placed in the "trip" state as shown in FIG. 25.
The conventional circuit breaker designed as described above suffers from the following difficulty: Installation of the auxiliary device 2 in the recess 3 with the auxiliary cover 4 removed as shown in FIG. 22 may be hazardous, because when the circuit breaker is in "on" state as shown in FIG. 23, the line connected to it is hot, and it may be tripped unintentionally.